RYX has been banned for being dumb so he asked me to post this here.
"Deathstroke has stage-specific instances where he is guaranteed a trait set-up. The two stages in particular being Metropolis Streets and the Fortress of Solitude. In Streets on the left side of the stage, there is a tank that shoots launched opponents. In Fortress of Solitude, there is a laser on the right. By launching your opponent and pressing the interact button to re-launch them, you have enough time for a safe trait setup. He can also do this off freezing hazards (Both Asylum Cell Blocks, Stryker's Island right corner) as well as the Watchtower's ship hazard(where they are lit on fire) I believe the Reactor left corner also sets this up, but I will have to double check. I'm not sure if you can guarantee trait set-ups in Themyscira's fire switches but I'm pretty sure you can do so off of the Insurgency's Brain hazard(right corner)
tl;dr Deathstroke can trait in Metropolis, FoS, Asylums, Stryker's, and Watchtower, possibly Themyscira and the Insurgency Brain hazard."